The present invention relates to vehicle suspensions, and more particularly to biasing elements for, and aftermarket conversions of, such suspensions.
Many types of vehicle suspension arrangements are well known. In recent years, it has become common to provide coil springs as biasing elements, with damping elements, commonly known as shock absorbers, connected between frame or unibody portions of the vehicle and suspension elements such as axle housings and pivotable arm members. In many cases, telescopic shock absorbers are mounted generally concentrically with coil springs. An examplary configuration has a spindle mount pivotally connected between upper and lower A-arms, a coil spring and coaxial shock absorber being interposed between the lower A-arm and a fixed point on the chassis. Another such configuration, known as the McPherson system, having a short axle housing or spindle rigidly connected at a bottom extremity of a shock absorber, a top extremity of the shock absorber being pivotally mounted to the vehicle chassis. A pivoting linkage locates the shock absorber bottom extremity and (for front suspensions, a suitable steering linkage) rotationaly orients the bottom extremity relative to a longitudinal axis of the shock absorber, a camber alignment of the suspension being maintained by the rigid connection of the axle housing or mount to the shock absorber. In this configuration, the unitary combination of the shock absorber, spring, and spindle or axle housing is known as a xe2x80x9cMcPherson strutxe2x80x9d.
In a significant number of cases, it is desired to change the ride height of the vehicle or other characteristics of the suspension. Accordingly, it has been common to substitute different springs and/or suspension components having different geometry. Also, increased ride height is sometimes achieved by inserting spacers between springs and connected suspension components.
A recent development is air suspension, wherein pressurized bellows are substituted for coil springs. However, the pressurized bellows of the prior art are incompatible with concentric mounting of shock absorbers. Another recent development is shock absorbers that are configured for receiving pressure air for selectively increased ride height, the pressure air augmenting conventional springs. A further development is hydraulic actuators that are substituted for conventional shock absorbers, the actuators being operable for changing the ride height. In typical xe2x80x9clow-riderxe2x80x9d applications, a downwardly extending piston rod of a hydraulic actuator connects to a lower suspension A-arm in place of a conventional shock absorber, an oppositely extending cylinder body being connected through a cut-down portion of the original coil spring to the vehicle chassis. An electrically driven pump feeds the single-acting actuator to change the ride height in response to operator input. A principal disadvantage of the low-rider actuators of the prior art is that they produce a particularly harsh ride with substantially no spring action because only about half of the original spring is utilized.
Thus there is a need for an adjustable vehicle suspension biasing element that is compatible with concentric shock absorber mounting and otherwise overcomes disadvantages of the prior art.
The present invention meets this need by providing an annular bellows unit that is particularly effective for use as an aftermarket vehicle suspension biasing element to replace a coil spring interposed between upper and lower spring mounts, the suspension also having a telescopic shock absorber or other element connected relative to the upper and lower spring mounts. In one aspect of the invention, the bellows unit includes an outer bellows having first and second ends; an annular first flange member sealingly connected at the first end of the outer bellows; an annular second flange member sealingly connected at the second end of the outer bellows; an inner bellows sealingly connected between the first and second flange members within the outer bellows member, a closed chamber being formed between the outer and inner bellows; and a fill passage extending through the second flange member in fluid communication with the chamber and having a fill port for pressurizing the chamber. Accordingly, a clearance passage for the telescopic element extends through the inner bellows and the annular flange members. One end of the inner bellows can encloses a portion of one of the flange members, an inner clamp ring clamping the end of the inner bellows to that flange member, which can also have a depression formed therein for engaging an inwardly extending projection that is formed on the one end of the inner bellows. The inwardly extending projection of the inner bellows can be ring-shaped, and the depression formed in the corresponding flange member can include a circular groove. Also, the inner bellows can have an inner bead-reinforcing ring aligned with the inwardly extending projection for reinforcing the inner bellows between the inner clamp ring and the circular groove.
One end of the outer bellows can encloses a portion of a corresponding flange member, the bellows unit also having an outer clamp ring clamping the outer bellows end to that flange member. The one end of the outer bellows can have an inwardly extending projection, and the corresponding flange member can have a depression formed therein for receiving by the projection. Alternatively, the depression can include a peripheral groove, and the outer clamp ring can deform a ring-shaped portion of the outer bellows into the groove.
The inner bellows can include a plurality of bellows segments having facing tapered elements that are joined at their outer peripheral extremities, with adjacent segments being joined between facing inner peripheral extremities of adjacent elements, respective outside reinforcing rings being connected proximate the facing outer peripheral extremities of corresponding bellows segments for reinforcing the segments against outside air pressure. The inner bellows can also have inside reinforcing rings that are connected proximate the facing inner peripheral extremities of adjacent segment elements.
In one preferred variation of the bellows unit, one of the flange members includes an outer flange and an axially separable inner flange, and the inner bellows has an outwardly projecting bellows flange portion, the bellows flange portion being sealingly clamped between the outer and inner flange portions. At least one of the outer and inner flange portions can have an axially facing depression formed therein, the bellows flange portion having an axially projecting enlargement that engages the axially facing depression.
In another preferred variation, the bellows unit also includes a tubular mandrel, and the inner bellows includes a facing pair of bellows elements and a neck portion that is joined between inner peripheral extremities of the bellows elements. The neck portion is reinforced by the mandrel, the bellows elements tapering axially inwardly toward opposite ends of the neck portion in an extended condition of the bellows unit. In a compressed condition of the bellows unit the bellows elements taper axially outwardly toward the ends of the neck portion. Thus the bellows elements undergo axial inversion when the bellows unit moves from the extended condition to the compressed condition, thereby facilitating an enhanced travel range of the bellows unit.
At least one end portion of the inner bellows can enclose an axially projecting extension portion of a corresponding flange member, an associated bellows element being folded inside the end portion of the inner bellows, projecting within the extension portion in the compressed condition of the bellows unit. Preferably the inner bellows is formed with respective flex regions at opposite extremities of each of the bellows elements, thereby facilitating movement between the extended and compressed conditions of the bellows unit.